diff --git a/app/models/design.rb b/app/models/design.rb
index aeacb79..b925147 100644
--- a/app/models/design.rb
+++ b/app/models/design.rb
@@ -8,6 +8,8 @@
 class Design < ApplicationRecord
   extend Mobility
 
+  NO_THEMES = %w[sutty-theme-none sutty-theme-custom].freeze
+
   translates :name, type: :string, locale_accessors: true
   translates :description, type: :text, locale_accessors: true
 
@@ -16,4 +18,8 @@ class Design < ApplicationRecord
   validates :name, presence: true, uniqueness: true
   validates :gem, presence: true, uniqueness: true
   validates :description, presence: true
+
+  def no_theme?
+    NO_THEMES.include? gem
+  end
 end
diff --git a/app/models/site.rb b/app/models/site.rb
index 3cb268b..ceeea4f 100644
--- a/app/models/site.rb
+++ b/app/models/site.rb
@@ -414,7 +414,7 @@ class Site < ApplicationRecord
   # TODO: Guardar la configuración también, quizás aprovechando algún
   # método de ActiveRecord para que lance un salvado recursivo.
   def sync_attributes_with_config!
-    config.theme = design.gem unless design.gem == 'sutty-theme-custom'
+    config.theme = design.gem unless design.no_theme?
     config.description = description
     config.title = title
     config.url = url